BACKGROUND: Pharmacy benefit can be purchased as part of an integrated medical and pharmacy health package-a carve-in model-or purchased separately and administered by an external pharmacy benefit manager-a carve-out model. Limited peer-reviewed information is available assessing differences in use and medical costs among carve-in versus carve-out populations.OBJECTIVE: To compare total medical costs per member per year (PMPY) and utilization between commercially self-insured members receiving carve-in to those receiving carve-out pharmacy benefits overall and by 7 chronic condition subgroups.METHODS: This study used deidentified data of members continuously enrolled in Cambia Health Solutions self-insured Blue plans without benefit changes from 2017 through 2018. Cambia covers 1.6 million members in Oregon, Washington, Idaho, and Utah. The medical cost PMPY comparison was performed using multivariable general linear regression with gamma distribution adjusting for age, gender, state, insured group size, case or disease management enrollment, 7 chronic diseases, risk score (illness severity proxy), and plan paid to total paid ratio (benefit richness proxy). Medical event objectives were assessed using multivariable logistic regression comparing odds of hospitalization and emergency department (ED) visit adjusting for the same covariates. Sensitivity analyses repeated the medical cost PMPY comparison excluding high-cost members, greater than $250,000 annually. Chronic condition subgroup analyses were performed using the same methods separately for members having asthma, coronary artery disease, chronic obstructive pulmonary disease, heart failure, diabetes mellitus, depression, and rheumatoid arthritis. RESULTS: There were 205,835 carve-in and 125,555 carve-out members meeting study criteria. Average age (SD) was 34.2 years (18.6) and risk score (SD) 1.1 (2.3) for carve-in versus 35.2 years (19.3) and 1.1 (2.4), respectively, for carve-out.